This Is What Star Formation in Colliding Galaxies Looks Like

These two galaxies are locked in a billion year dance.

NASA/ESA

By
Sophie Weiner

The photo above depicts something quite incredible: a snapshot of two entangled galaxies, captured by the Hubble Telescope. The galaxies NGC 4490 and the smaller NGC 4485 have been locked in a gravitational dance for millions of years, at one point colliding. That was a long time ago—the galaxies have now passed through each other and are speeding apart again. But gravity is strong and it's only a matter of time until their incredible mass sucks them back together.

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All of this intergalactic mixing has created dense mixtures of gasses that are perfect for star formation. The patches of brilliant pink light in the image are clouds of ionized hydrogen, lit up by the ultraviolet light emanating from hot young stars. These two galaxies also contain a bridge of stars created by their collision that stretches for 24,000 light years between them. Due to all this stellar activity, scientists have labelled NGC 4490 a "starburst galaxy."

NGC 4490 and NGC 4485 are located about 24 million light-years from Earth in the constellation Canes Venatici. That means that this image is actually looking far into the past—in the 24 million years since this light left the galaxies, many new stars have formed and died. Scientists have spotted several supernovae in the galaxies over the last few years. For all we know, a star being formed in this image has already lived, died, and reformed into another star. All we can do is look at these images and wonder.